This invention relates to the art of stands for metalworking machine and, more particularly, to foldable a stand for a power driven threading machine.
The use of portable power driven pipe and rod threading machines to facilitate the on site preparation of threaded pipe and rod is of course well known, and it is likewise well known to provide a stand to support such a machine during metalworking operations. Certain such stands heretofore provided have included four ground or floor engaging legs while others have included a pair of such legs and a pair of wheels which facilitate lifting one end of the stand for the stand and the machine mounted thereon to be supported by the wheels for movement from one location to another along an underlying support surface such as a floor or ground.
While stands of the foregoing character adequately serve to support the threading machine during operation thereof and provide a degree of portability with respect to the machine, a number of problems are encountered in connection with both the portability and transportability of the machine and stand. In this respect, the loading or unloading of the stand and machine thereon relative to the bed of a truck, a loading dock or the like, may require the use of a forklift truck, an elongated ramp if the stand is wheeled, and/or the physical efforts of at least two workmen, especially in connection with physically lifting or lowering the stand and machine relative to a truck bed or dock. In connection with wheeling the stand and machine up or down a ramp, or physically lifting or lowering the stand and machine, it will be appreciated that the vast majority of the weight of the stand and machine is that of the machine alone, which may for example be 150 to 200 pounds, and that the center of gravity of the stand and machine is therefore relatively high with respect to the underlying support surface, therefore, extreme care must be taken to avoid tipping of the stand and machine during such movement thereof, adding to the physical exertion on the part of the workmen in connection with such loading or unloading operations. Furthermore, if it is necessary to move the stand and machine up or down a stairway to or from a location of use, storage or like, the tipping and physical exertion problems are multiplied. Further in connection with moving the stand and machine up or down a stairway, the wheels of wheeled stands heretofore provided interfere with such movement and add to the difficulty and physical exertion required in connection therewith by engaging against the stair riser in moving up the stairs and by having to drop along the riser between adjacent steps in going down the stairs. Accordingly, it will be appreciated that the transportation of such stands with threading machines mounted thereon is time consuming, physically tiring, and can be extremely hazardous for the workmen and potentially damaging to the machine should tipping occur.
It has been proposed to provide a foldable stand for threading machines comprised of a scissors-like leg assembly having ground engaging wheel and handle components and which is spring loaded to be moved from the folded to the extended position with the metalworking machine mounted thereon. When folded, the wheels and handle facilitate elevating one end of the stand and machine relative to ground for the stand and machine to be supported by the wheels for movement from one location to another. However, the spring force required to facilitate displacement of the stand and machine to the extended position and to maintain the latter position is such that the folding and extending operations are hazardous to a workman and can lead to injury. Furthermore, while the collapsing does lower the center of gravity of the machine so as to reduce the problem of tipping in connection with transportation of the stand and machine, the loading or unloading of the stand and machine relative to a truck bed or movement of the stand and machine up or down a stairway remains time consuming and physically demanding on the part of the workmen performing these tasks. The latter is due at least in part to the interference of the wheels of the stand with such movement thereof as described above.
Another problem encountered in connection with pipe threading machine stands heretofore provided is the susceptibility thereof to tilting about an axis transverse to the machine axis under certain work loading conditions. In this respect, such machines are capable of threading one end of an elongated pipe or rod which can extend a considerable distance beyond the end of the machine opposite the end at which threading takes place. Accordingly, if the length of the workpiece extending from the machine is too long, the weight thereof, unless separately supported, will tilt the machine relative to the underlying surface. Therefore, either a separate workpiece supporting stand is required to preclude such tilting, or operation of the machine must be limited to predetermined lengths of workpieces. Even in connection with the latter, it will be appreciated that if the workman accidentally tries to thread a workpiece which is too long, the stand and machine may tilt in the foregoing manner. Any such tilting endangers the workman and is potentially damaging to the machine.
Yet another problem encountered in connection with such stands heretofore provided is that storage of the stand and machine mounted thereon consumes considerable floor space. Even if the stand is foldable, the latter and the machine mounted thereon are in a horizontal disposition when stored and, thus, require a floor area for storage at least equal to the area of the stand and machine during use. In connection with a foldable stand, the latter may require a greater floor area for storage when folded than than unfolded. Still a further disadvantage results from the fact that the threading machine has but one working position which is at a fixed elevation relative to ground, whereby operation of the machine may be uncomfortable or awkward for many workmen.